Dendrobium Orchids Plant Care Guide

Samantha GreenMonday, April 2, 2012

In the United States, the Dendrobium orchid is second only to the Phalaenopsis in popularity. It’s profuse, often delicate, blooms cascade from trees where its robust roots cling. While this guide covers specific tips for Dendrobiums, make sure to review Orchid Care Guide for All Types, which provides general orchid care instruction relevant to the Dendrobium as well.

Dendrobium Orchid Care Basics

These quick tips are followed by more in-depth information about pruning and propagating Dendrobium orchids as well as specific care instructions for each phase of its life cycle.

Light: One of the more light-tolerant orchids, the Dendrobium can tolerate full morning sun followed by an afternoon of shade.

Temperature: Day: 68-85° F; Night: 65–75°F. Plant should have even temperature if possible, especially when in bud. Chilly temperatures or drafty areas can cause flowers and buds to drop from many Dendrobium species.

Water: Water about once a week: it’s best to allow medium to almost dry out between watering. Check the medium with your finger - if you feel moisture do not water. Do not let stand in water.

Fertilizer: When your orchid is blooming, fertilizer is not needed. During growth phase (summer), add a balanced fertilizer (12-12-12) at one-quarter strength with every other watering. Stop fertilizing in fall. If no new growth appears by January, consider a high phosphorus fertilizer (such as 10-30-20) to kick-start the blooming process.

Growth: Orchids can double in size in a year with the correct growing conditions

Blooming: Emerging in February, Dendrobium orchid blooms tend to last about 6 weeks, and re-bloom in cool temps up to 3 times a year.

Dendrobium Orchid Care Throughout Its Life Cycle

The life cycle of the Dendrobium orchid includes:

flowering phase: winter to spring in the northern hemisphere,

growing phase: summer to fall

dormancy: late fall to winter

Flowering Phase Orchid Care -- February - June

What’s happening: Bloom sprays appear from the top of the canes. Anywhere from 5-20 flowers will bloom on each cane. Blooms last from one to three months.

What to do: Water weekly, but do not fertilize. Consider putting plant on a humidity tray (cookie sheet lined with pebble and filled with water) or spritzing daily in the morning.

Growing Phase (Post-Bloom) Care – June - September

What’s happening? The blooms die, but the leaves begin growing rapidly. The plant has the potential to double in size in a year.

What to do: When the blooms are done, cut the sprays just where they meet the canes. Canes may produce several sprays from the upper leaf axils each year. Fertilize with high nitrogen fertilizer to support this rapid plant growth. Water weekly and use a balanced fertilizer (12-12-12) twice each month. It’s at this point that many growers repot the Dendrobium to optimize its potential for growth.

Your Dendrobium may also surprise you with a new arrival . . . a “baby” or keiki in Hawaiian. If a mini-plant starts growing alongside the original plant, congratulations (and repotting) are in order. Read below for specifics on how to separate the pair.

Rather than trying to re-bloom from the same cane, growers sometimes cut the spent canes at their base and lay them on moist river sand or bark. Only the Dendrobium propagates by producing keikis or “babies” at each node from dead canes. At the end of the growing season, keikis can be removed and planted.

Dendrobium Orchid Care When Dormant – Sept - January

What’s happening: Orchid leaves stop growing so that plant energy can focus on roots instead. Growth starts again at the end of the rest phase with a stem sprouting from the plant, signaling returned need for fertilizer and water.

What to do: When fall rolls around, give your orchid a rest by putting it in a cooler room with lower light, less water and refrain from fertilizing. Some growers even recommend you forget your Dendrobium. If after six weeks no new stem has started, use a high phosphorous (10-30-20) fertilizer to get blooming going.

Repotting the Dendrobium

What’s happening? Where the Cymbidium can go for three years before needing repotting, many growers repot the Dendrobium every year after blooms have died. This epiphyte doesn’t want dense potting mix (see how bare its roots are bare on that tree in the photo below), so when the bark breaks down and impedes air flow to the roots, it’s time for a new substrate. The plant itself will tell you it needs new digs if it starts growing over the edge of the pot or spawns a miniature version of itself, a “keiki” (baby in Hawaiian dialect.)

What To Do:

Materials: A good Dendrobium potting mix like a fine fir bark potting mix; sharp, sterilized scissors or secateurs; Dendrobium pot just one inch larger than original (“over-potting” can reduce bloom initiation and growth). Clay pots, which allow for more air exchange, are a best bet for this epiphyte.

Gently pull the orchid from the pot and shake loose the remaining potting mix. If orchid is being stubborn, consider soaking plant, pot and all, in water. If that doesn’t work, cut or hammer off the pot. A few pot pieces stuck to roots won’t impede growth in the new pot. Better to leave these on that cut roots to remove them.

Trim any dead or rotting roots with sterilized blade. Never use blade on another plant without re-sterilizing.

Add potting mix to ½ inch of pot rim. Work roots into mix, but do not bury the base of the pseudobulb. Use a rhizome clip if you need it to secure the plant.

Stabilize plant with a vertical stake and ties

Water sparingly until new roots start.

The Dendrobium Outdoors

Light-loving (for an orchid that is), the Dendrobium plant loves to go outdoors, particularly in the summer in humid climates. In fact, many spend June through September in the fresh air. Of course, you can’t plant it permanently outside in most hardiness zones as the first frost or even a few 40° days will kill it. Keep it in partial sun/partial shade. Bring plants in if many days of rain threaten. Too much water will cause root rot. Keep bugs at bay by setting pot on a stand rather than directly on the ground.

As mentioned above, the Dendrobium reproduces by growing keikis or “babies” from the nodes on the stem. After flowers have bloomed, cut stem at the base and lay it on moistened river sand, Dendrobium potting mix or fir bark. Allow keikis to grow until the end of the growing season (August). These keikis should grow roots. Remove and pot them in small pots.

Dendrobium Orchid Origin and Background

With 1,600 species within the Dendrobium genus, those who get the Dendrobium bug must research the orchid care details of their specific orchid type. Stopping at Dendrobium is not enough; rather you’ll need to know if you have a heat-craving Dendrobium antennatum or the more tolerant Dendrobiumkingianum, which can be left outside late into fall and even withstand a light frost! There are both deciduous and evergreen Dendrobium orchids, and the two groups have differing care requirements. Warm-climate, intermediate-climate and even cool climate Dendrobium species have differing needs as well. Therefore, the most crucial care tip for the Dendrobium beginner is: keep the plant’s tag or ask the grower the species of orchid!

The one detail that orients all of us, however, is the fact that the Dendrobium is epiphytic, growing exclusively on trees in diverse climates from Asia to New

Zealand. That means it’s used to pulling its nutrients and water through its bare roots from moist air. Two care mandates result: airy potting mix that should be kept only barely damp and a moist environment (humidity levels from 50% - 70%).

That’s where broad guidelines end. Some Dendrobium orchids refuse to bloom if they can’t experience an extended cold snap. Others need weeks of dry potting mix before realizing it’s time to send up a flower spike. Luckily, typing your exact orchid flower’s genus and species into a search engine followed by “care” will turn up at least one other orchid lover who’s a little ahead of you. Usually, the D. heterocarpum (or any other species)experts are willing to share how to care for orchids from even the most rare lines.